U. S. DEPARTMENT OF AGRICULTURE, 



BUREAU OF ANIMAL INDUSTRY.— Bulletin No. 89. 

A. D. MELVIN, Chief ok Bureau. 



SF 

CKn 

INVESTIGATIONS IN THE MANUFACTURE 
AND STORAGE OF BUTTER. 



II.-PREVENTING MOLDS IN BUTTER TUBS. 



BY 



L. A. ROGERS, 

Bacteriological Chemist, Dairy Division, 
Buteau of Animal Industry. 




WASHINGTON: 

GOVERNMENT PRINTING OFFICE. 

1906. 



ESonotf"** 




Class. 
Book_ 



U. S. DEPARTMENT OF AGRICULTURE, 

BUREAU OF ANIMAL INDUSTRY.— Bulletin No. 89. 

A. D. MELVIN, Chief of Bureau. 






INVESTIGATIONS IN THE MANUFACTURE 
AND STORAGE OF BUTTER. 



II -PREVENTING MOLDS IN BUTTER TUBS. 



BY 



L. A. ROGERS, 



Bacteriological Chemist, Dairy Division, 
Bureau of Animal Industry . 




WASHINGTON: 

GOVERNMENT PRINTING OFFICE. 
1906. 



■■ograph 






ORGANIZATION OF THE DAIRY DIVISION. 



Chief: Ed. H. Webster. 
Assistant Chief: C. B. Lane. 
Assistant: Wm. Hart Dexter. 



ADMINISTRATION. 



SCIENTIFIC STAFF. 



Butter investigations: Chief, in charge; C. E. Gray, chemist and experimental maker; 
C. W. Fryhofer, assistant; E. A. McDonald, W. S. Smarzo, W. J. Credicott, market 
inspectors. 

Market milk investigations: Assistant Chief, in charge; R. H.Shaw, chemist; George M. 
Whitaker, assistant. 

Cheese investigations: C. F. Doane, in charge. American varieties: John L. Sammis, chem- 
ist; Jay W. Moore, expert maker. European varieties: Charles Thom, mycologist; 
Arthur W. Dox, chemist; T. W. Tssajeff, expert maker. 

Southern dairy investigations: B. H. Rawl, in charge; H. N. Slater, Duncan Stuart, J. A. 
Conovei, S. E. Barnes, J. W. Ridgeway, J. E. Dorman, assistants. 

Building and management inivstigations: B. D. White, in charge; G. H. Parks, architect. 

Dairy laboratories: C. E. Gray, chemist; L. A. Rogers, bacteriological chemist. 

INSPECTION STAFF. 

Renovated butter factories: M.W.Lang, 510 Northwestern Building, Chicago, 111., in charge. 

Renovated butter markets: Levi Wells, Laceyville, Pa., in charge. 

Inspectors: Robert McAdam, 510 Northwestern Building, Chicago, 111.; George M. Whit- 
aker, Washington, D. C; E. A. McDonald, Seattle, Wash. 

Deputy inspectors: S. B. Willis, Boston, Mass.; R. A. McBride, J. PI. Barrett, 6 Harrison 
street, New York, N. Y. 

2 



OCT 15 1906 
D.ofD, 






LETTER OF TRANSMITTAL. 



U. S. Department of Agriculture, 

Bureau of Animal Industry, 

Washington, D. C, July 14, 1906. 
Sir: I have the honor to transmit herewith, and to recommend 
for publication as a bulletin of this Bureau, a manuscript entitled 
"Preventing Molds in Butter Tubs," by L. A. Rogers, bacteriolog- 
ical chemist in the Dairy Division. This paper is the second in a 
series on Investigations in the Manufacture and Storage of Butter. 
Acknowledgment is made of courtesies and facilities extended by 
the managers of the creameries at Eagle Lake, Minn., and Bloomer, 
Wis., and by the Fox River Butter Compan}" in connection with the 
experiments reported in this bulletin. 
Respectfully, 

A. D. Melvin, 
Chief of Bureau. 
Hon. James Wilson, 

Secretary of Agriculture. 



CONTENTS 



< londitions favoring the growth of molds 7 

Propagation of molds 8 

Growth of molds in butter tubs 8 

Prevention of molds in tubs 9 

Testing and comparison of methods 9 

Method of applying paraffin 11 

Cost of paraffining tubs - . 12 

Summary 13 



ILLUSTRATION. 



Fj(;. 1. Apparatus for paraffining tubs 12 



PREVENTING MOLDS IN BUTTER TUBS. 



There is probably no one trouble that causes butter dealers so 
much annoyance as the growth of molds on the inside of butter tubs. 
This is a trouble that is not confined to any one geographical sec- 
tion or to any one type of factory. It may be only an occasional 
outbreak even in the best managed factory, or it may become a 
chronic condition which the buttermaker is unable to control. 

Before discussing the methods of preventing the growth of molds 
in tubs it will be well to consider briefly some of the characteristics 
of these tiny plants and the conditions under which they grow. 

CONDITIONS FAVORING THE GROWTH OF MOLDS. 

Molds are plants and obey certain fixed laws governing the group 
of which they are a type. They differ from the common plants 
with which we are familiar in everyday life in that they possess none 
of the green coloring matter by which the higher plants utilize the 
energy of the sun's rays in building up their tissues. Hence they live 
as well or better in darkness than in light, but are limited for their 
food supply to materials that have been prepared for them by ani- 
mals or by other plants. Almost any animal or vegetable matter 
serves them for food. We find them growing on bread, meat, bones, 
clamp wood, leather, and many other things. Sugars and many of 
the acids may be used, and we frequently find a luxuriant growth 
of mold on foods containing sufficient sugar or acid to prevent the 
growth of bacteria or yeasts. 

A certain amount of moisture is necessary for the growth of molds. 
Growth will not occur on the surface of wood or leather unless it is 
allowed to remain in a damp place. 

Oxygen is necessary to the development of all living things. 
Some of the bacteria which live only under conditions that exclude 
air completely seem to be an exception to this rule. These forms, 
however, obtain their oxygen from certain constituents of their 
food. The molds are unable to do this, and, like the higher plants, 
live only where there is at least a limited supply of air. 

While a certain amount of heat is essential to the growth of molds, 
there is a wide range of temperature under which growth is possible. 
Many of the molds grow most rapidly at blood heat, but continue 
to grow slowly at temperatures near the freezing point. Other 
varieties find the most favorable conditions at lower temperatures 
and grow with comparative rapidity in ordinary refrigerators. 

7 



8 MANUFACTURE AND STORAGE OF BUTTER. 

PROPAGATION OF MOLDS. 

Molds reproduce themselves by yeastlike buds or by spores which 
correspond more closely to the seeds of higher plants. The buds, 
or conidia, as they are called, are easily destroyed; the spores, on 
the other hand, on account of their peculiar structure, resist for 
some time conditions that would destroy the mold itself almost 
instantly. Spores may be dried for years and yet under favorable 
conditions they will germinate and in a surprisingly short time pro- 
duce a mycelium bearing millions of spores. They are able to endure 
much more heat than the mold itself, but are destroyed by a short 
exposure to boiling water. In a dry condition they are much more 
resistant. 

Short exposures to disinfectants destroy the spores, but molds 
readily adapt themselves to unfavorable conditions and are fre- 
quently found growing in the presence of antiseptic sufficient to 
inhibit completely the growth of bacteria. 

These spores and conidia are formed in enormous numbers, and 
on account of their minute size and exceedingly light weight are 
carried about by every movement of air. It is therefore almost 
impossible in practice to prevent entirely infection by molds. The 
most efficient means of holding them in check is to provide condi- 
tions unfavorable to their growth. This may be done by depriving 
them of one or more of the factors — food, air, moisture, or heat — 
which have been mentioned as essential to their growth. 

GROWTH OF MOLDS IN BUTTER TUBS. 

Tubs can not be made or transported without contamination, 
but if they are reasonably dry the spores will not germinate. If, 
however, the wood is not well seasoned, or if the finished tubs are 
held at the factory in a damp storeroom, the few spores grow and 
in a short time the surface of the wood is covered with a growth of 
mold. The tub may come from the factory in good condition and 
be stored in the creamery in a damp place. This may be in the ice 
house or next to the damp wall of the ice house or refrigerator. The 
growth of mold may not be noticeable without close examination. 
When the tubs are filled with butter, the air is excluded and the 
molds are unable to grow, but after a few days the evaporation of 
water causes the butter to shrink away from the tub, leaving a very 
small air space. Favorable conditions of food, moisture, and air 
are thus provided, and if the temperature is not too low growth will 
begin again. 

It is a common belief that moldy refrigerators are responsible for 
mold in butter tubs, but from the nature of the package it is very 
improbable that the inside of the tub could become contaminated 
after it is filled. Temperature and moisture conditions that would 



PREVENTING MOLDS IN BUTTER TUBS. 9 

allow molds to grow on the wall of a refrigerator would favor the 
growth of molds on the inside of the tub, but the infection must come 
before the tub is put in the refrigerator. The growth of molds on 
the walls could be prevented by occasionally wiping the wall with a 
cloth moistened in a 5 per cent glycerin solution of corrosive sub- 
limate. This would give the wall a thin, sticky coating in which the 
floating spores would be held and destroyed. 

PREVENTION OF MOLDS IN TUBS. 

The growth of molds in the tub may be prevented more or less 
successfully (1) by storing the tubs in a dry place, (2) by storing 
the butter at a temperature below the growth point, (3) by treating 
the tubs in some way to destroy the molds and their spores, or (4) 
by treating the tubs with some preparation on which molds can not 
grow. 

The tubs may come to the butter maker badly infected, or he may 
not have at his command suitable storage. Few creameries have 
refrigerators holding a temperature low enough to inhibit the growth 
of molds if other conditions are favorable. The butter maker is 
therefore frequently forced to resort to the third method. 

The method of steaming the tubs is often used to destroy the molds, 
but this has not been very effective. It is difficult to heat the tub 
thoroughly by a steam jet, and the sudden swelling of the tub fre- 
quently breaks the hoops. 

Soaking in a brine containing about 5 per cent of formaldehyde is 
a method sometimes used, and one commission house recommends 
that the tubs be boiled in brine and that salt be rubbed on the inside 
before packing. 

A few of the larger factories have recently begun coating the inside 
of the tubs and boxes with paraffin. This not only destroys the molds 
already present but gives a surface on which molds will not grow. 

TESTING AND COMPARISON OF METHODS. 

Various methods were tested and compared by the writer in a 
creamery wmich had had serious trouble with molds all through the pre- 
vious summer. The test was made in October, when the temperature 
conditions were becoming unfavorable to the growth of molds. The 
factory was a new one, in excellent condition, and the refrigerator, 
which was better than the average, was free from molds. However, 
the tubs were stored in a damp room on the north side of the cream- 
ery. The practice had been to submerge the tubs on the day before 
they were used in a saturated brine which was boiled by blowing 
steam into it, and to allow them to stand in the warm brine over- 
night. Before packing, the sides of the tubs were coated with salt. 
This had not proved entirely effective. 



10 



MANUFACTURE AND STORAGE OF BUTTER. 



For the experimental work thirty 20-pound tubs were secured and 
divided into six lots of five each. Lot I was old tubs from various 
sources, all showing; more or less mold, while some were very moldy. 
Lots IT, III, IV, and V were new tubs received direct from the factory. 
Nearly all had a ring of mold where the tubs were in contact. The 
tubs of Lot II were purposely wet with an emulsion of moldy cheese. 
Lot VI was new tubs showing no mold. 

The tubs of each lot were numbered from 1 to 5. Tub No. 1 in 
each lot was soaked overnight in cold water in the usual way; No. 
2 was boiled five minutes in a saturated brine and left in the brine 
overnight; No. 3 was soaked overnight in a brine containing 9 per 
cent of commercial formalin; No. 4 was coated on the inside with 
paraffin, the paraffin being applied either with a paint brush or by 
pouring, while hot, into the tub, which was rotated until the fluid 
had flowed over the entire inside surface; No. 5 was immersed for a 
few seconds in a bath of paraffin at 250° to 260° F. In each case 
the liners were soaked in a salt solution. 

All of the tubs in each lot were filled from the same churning and 
all held in the creamery refrigerator until shipped. The first lot was 
held ten days, the second nine, the third eight, the fourth seven, the 
fifth six, and the last lot five days before shipment. The butter was 
shipped in a refrigerator car and was received at Aurora, 111., six days 
later and was examined the following day. The results of the exam- 
ination are given in the following table. In this table the tubs are 
described as moldy only when there was an evident increase of the 
mold originally on the tub. 

Table showing results of experiments in treating tubs for prevention of mold. 



Lot No. 


Tub No. 


Treatment. 


Condition. 




1 ! 
! i 

2 
\ 3 

4 
I 5 
f I 

2 
\ 3 

4 
I s 

! ! 

1 * 

3 

1 1 












I. 


Brine-formakleh yde 

Coated with paraffin 

nipped in paraffin 

Untreated 


Do. 
Do. 
Do. 
Tub and liner badly molded. 
Do. 


II. 


Brine-formaldehyde 


No mold. 
Do. 






Do. 












Two small spots of mold on tub and liner. 


III. 








Do. 






Do. 






Slightly moldy. 






IV. 
















Do. 














V. 




Do. 






Do. 






Do. 






Tub and liner moldy. 






VI. 




Do. 




Coated with paraffin 


Do. 

Do. 









PREVENTING MOLDS IN BUTTER TUBS. 11 

It will be seen from this table that all of the untreated tubs became 
moldy. Of the six tubs treated with hot brine one was badly molded, 
one was slightly molded, and one had mold on the outside. Of the 
six tubs soaked in the brine-formaldehyde mixture one was badly- 
molded. None of the tubs coated with paraffin showed any mold 
whatever, and the same was true of those dipped in paraffin . 

It was evident that each of these methods checked the growth of 
mold materially, but that paraffining was -much more efficient than 
the other two methods. If the temperature conditions had been 
more favorable to the molds it is probable that these differences 
would have been greater. 

This test, so far as it goes, indicates that the formaldehyde treat- 
ment is more efficient than the hot-brine method. Salt is at best a 
weak antiseptic. Gripenberg a has shown that while the growth of 
Penicillium, the mold most commonly found on butter, is retarded 
by 5 per cent of salt, it will grow slowly in 10 and even 20 per cent 
solutions. Twenty-five per cent of salt completely checked its 
growth. 

To treat tubs by the brine-formaldehyde method or the hot-brine 
method a vat should be made large enough to hold submerged the 
tubs used in one day. The brine may be boiled by blowing steam 
into it. The cost of either of these two methods is insignificant, as 
the bath may be used repeatedly. The objections to these methods, 
in addition to their inefficiency, would probably be found in the dis- 
coloring of the wood and, with the hot brine, in the excessive weight 
and swelling of the tub. 

With paraffining not only are the molds and their spores already 
on the tub prevented from growing, but the wood is covered with a 
surface from which molds can not get nourishment. The wood is 
made impervious to water, and the space between the tub and the 
liner remains filled with water, so that the molds which may be on 
the liner can not get the supply of air necessary to their growth. The 
appearance of the tub is unchanged and is better than that of tubs 
soaked in brine or water. 

There is no advantage in dipping the tubs over coating the inside, 
except that the outside will not become moldy. Dipping has the 
disadvantage of extra cost and giving the outside of the tub a surface 
which can not be marked with a pencil. 

METHOD OF APPLYING PARAFFIN. 

The paraffin should be applied in such a way that it will give an 
even, thin coating which fills all the cracks and at the same time sinks 



a Gripenberg, R. Untersuchungen iiber Schimmelbildung bei Lagerbutter. Meddel 
Mustiala Inst. Forsoksstat Mijiriafd, Helsingfors, 1899. Review in Milch Zeitung, v. 28, 
No. 40, pp. 626-628; No. 41, pp. 644-646. Bremen, 1899. 



12 



MANUFACTURE AND STORAGE OF BUTTER. 



into the wood sufficiently to prevent the coating of paraffin from 
cracking off. The application may be made with a brush, but it may 
also be accomplished by pouring a small amount of the melted paraffin 
into the tub and rotating the tub until the paraffin has flowed over 
the entire surface, taking care that it does not run down the outside 
of the tub. By the latter method a thinner, evener coating may be 
applied than by using a brush. 

The temperature of the paraffin is important. If the temperature 
is too low, the paraffin will cool rapidly, making a thick uneven coat- 
ing; if the paraffin is too hot, it will sink into the wood and the cracks 
will not be closed up. If the paraffin is melted by holding the 
receptacle in hot water or steam, it will be found advantageous to 
heat the tub over a steam jet. 

The paraffin can be applied most rapidly and satisfactorily by 
heating it to 250° or 260° F. This may be done on an oil stove, but 
in creameries where steam is always available it will be better to 
arrange a small tank with a steam coil, as shown in figure 1. 



tzja/m /e'en**** 
■%xi"bam> — 

%^rr£C TO &*l. TXWt 




mow SOJlff? 



Fig. 1.— Apparatus for paraffining tubs. 



By connecting the coil in the bottom of the tank with the boiler 
and opening the waste valve only enough to allow the escape of the 
water of condensation, boiler pressure may be maintained in the coil 
and the temperature of the paraffin raised to the required point. 



COST OF PARAFFINING TUBS. 



The question of the cost of paraffining tubs will doubtless be 
brought up as an objection to this method. The amount of paraffin 
necessary to coat a 60-pound tub will vary with the method of apply- 
ing and the temperature of the paraffin. If the paraffin is hot enough, 



PREVENTING MOLDS IN BUTTER TUBS. 13 

this should not exceed 3 ounces per tub, and as a good grade of par- 
affin may be purchased at about 8J cents a pound the cost will be less 
than 2 cents per tub. But even this small sum would be a consider- 
able item in a season's run and would be a serious objection in some 
factories. However, there is another factor which must be taken 
into consideration. In an ordinary tub the loss by evaporation 
from the outside and by absorption of water from the butter by the 
tub is an appreciable quantity. Coating the tub with paraffin makes 
it impervious to water, and this loss is reduced to a minimum. 

To illustrate this point, 24 tubs were divided into two lots of 12 tubs 
each. One lot was paraffined in the manner previously described, 
and the other lot was soaked overnight with cold water in the usual 
way. The tubs were weighed before filling and again after the butter 
was packed. The 12 paraffined tubs contained at this time 757 \ 
pounds of butter and the 12 tubs soaked in water 766| pounds. These 
tubs were all filled from the same lot of butter, were held in the 
factory refrigerator three days, and were then shipped to the com- 
mission house, where they were weighed on the eighth day after 
packing. Each tub was weighed separately, and the average weight 
of three empty tubs was taken as the tare. The weight of butter 
obtained in this way was for the paraffined tubs 756 pounds, a loss of 
1\ pounds; for the soaked tubs 759 pounds, a loss of 7 1 pounds. In 
other words, by the use of about 15 cents' worth of paraffin the price 
of 6 pounds of butter was saved. In butter held in storage for any 
length of time this saving would undoubtedly be much greater. 

It should be remembered, however, that paraffined tubs weigh from 
1 to 2 pounds less than tubs prepared in the ordinary way, and unless 
the tare is actually determined this difference will be lost to the 
butter maker. This possibility may be avoided by soaking the tubs 
before paraffining. To do this it is necessary to keep the paraffin 
very hot, so that it will displace the water in the pores of the wood, 
or the soaked tub may be heated on a steam jet before applying the 
paraffin. 

The labor cost of paraffining need not be greater than in the usual 
method of soaking tubs in cold water or brine. The apparatus needed 
as here illustrated is simple and inexpensive. 

SUMMARY. 

The advantages of paraffining may be summarized as follows: 

(1) Certain prevention of moldy tubs. 

(2) Prevention of mold on butter and liner by avoiding air space. 

(3) Neater appearance of tub. 

(4) Reduction of loss from shrinkage. 

O 



LBFe'07 



